Electric circuit protector



Dec. 22, 1953 w. D. MATTHEWS ET AL 2,663,778

ELECTRIC CIRCUIT PROTECTOR 2 Sheets-Sheet l Fxhd Feb. 14, 1951INVENTOR5. William D, Matthews BY Thomas E. Curt/o Dec. 22, 1953 w. D.MATTHEWS ET AL 63,778

ELECTRIC CIRCUIT PROTECTOR Filed Feb. 14, 1951 2 Sheets-Sheet 2 lINVENTORS. 36 \37 William D. Matthews Thomas E. Curl-is Fe. 6

Patented Dec. 22, 1953 ELECTRIC CIRCUIT PROTECTOR William D. Matthews,Atlanta, and Thomas E. Curtis, Hampton, Ga., assignors to, Southern,States Equipment Corporation, a corporation 2 Ge r Application February14, 1951, Serial N 0. 211L810 1 10 Claims.

The object of this invention is to prevent one conductor of an electriccircuit from remaining charged after another conductor has beenopencircuited, as by the blowing of a fuse.

One purpose is to provide a grounding means to prevent a two-phase or athree-phase electric motor from continuing to operate on a single phaseafter the blowing of one of the fuses through which the motor receivespower; another purpose to provide a simple, low cost device for thisuse; another purpose is to make a device which applies the force of thehammerblow of a falling fuseholder directly to releasing the groundingmembers so they may function; another purpose is to provide a simplemeans to prevent an accidental grounding operation whil blown fuselinksare being replaced; and other purposes will be evident from thespecification and claims.

The present device is somewhat similar to that shown in U. S. Patent No.2,089,387, but the present device has fewer parts, it can be made atlower cost and it functions more efficienty. The invention can be usedin conjunction with repeater fuses or with only a single dropout fuse ineach conductor, and the operation is the same. in each case. In thepresent specification and drawing single fuses are shown.

In the drawings, Figure 1 shows a front View of three dropout fuses withone form of this invention installed below the fuses; Figure 2 is a sideview on the plane 2-2 in Figure 1; Figures 3, 4, 5-, and 6 are sideviews of the latch l5 on the sectional plane 3;% in Figure 1; Figure 7is a large scale front view of box 2| with the cover removed; and Figure8 is a similar side view of the box, on the section line 2-4! in Figure7.

Referring to Figures 1 and 2, the support holds two insulators 2, 3 witha conductive terminal on each insulator, and an expulsion-tubefuseholder hinged at terminal 5 and latched, into position at terminal6. A grounding contact 1 is secured to terminal 5. Three conductors A!2, BiB2 and C|C2 constitute the three-phase circuit which the threedropout fuses protect. ihe dropout fuses are all alike. The termconductor in the specification and claims is understood to designate thefuselink inside of each fuseholder and also all conductive members whichnormally are electrically connected with such fuselink.

Spaced below the fuseholders and rotatably supported, as by angle clips8, 8, 8, are the grounding bar 9 and the operating bar ID. Secured tothe grounding bar 9 are three grounding members which are movable intoand out of contact with grounding contacts li, respectively. Secured tooperating bar 19 are three trip members |2 |2, each being in position tobe struck by its respective fuseholder when the fuseholder drops bygravity to its opencircuit position as shown by dotted lines in Figure2.

Also secured to grounding bar 9 is the curved reset crank |3 with pivotM at its swing end. See Figures 3, i, 5 and 6. Supported on pivot i4 islatch l5 which is partially box-shaped with two sides cut away atrecesses H3, with a hole in the front side, with a reset ring t1 and arelease ring 18. Collar i9 is secured to operating bar IQ and it has aprojection 20 for engagement with the upper edge of the hole in latchI5, as shown in Figures 1 and 5.

Intermediate between the two ends of each of said bars 9 and H), is thehousing 2|, which is suitably held as by support 22. See Figures 2, 7and 8. Spring shaft 23 passes through box 2| and about it is springcollar 24- Which is secured to shaft 23 by screw 25. One end ofoperating spring 28 enters the hole 2''! in collar 24, and pin 28connects toggle link 29 with crank 24' on collar 24. Pin 30 connectslink 29 with crank 3| on trip collar 32, which is bifurcated and looseon shaft 33. Between the two forks of collar 32 is collar 31-31, whichcollar is securely held to operating shaft 33 by screw 34. Spring 35biases collar 32 clockwise, in Figure 8. Stop 35 engages projection 31to limit the clockwise motion of collar 32.

Crank 3| and link 25 together form a toggle of which the, pin 3]] formsthe center joint, and

when this toggle is past center it constitutes a definite holdingmechanism to withstand the bias of operating spring 26, Adjusting screw38 determines the travel of this tog le past center. When crank 31 isturned counterclockwise collar 24 rotates clockwise under the bias ofoperating spring 26 until projection 39 reaches stop 40. Pins 4|, 4| and42, 42 connect shafts 23 and 3.3, respectively, with the two portionseach of bars 9 and i0, preferably by non-ri id joints. Part by spring 26extends into cup 43, which is part of housing box 2|, and one end 45 ofspring 26 projects down through a hole in cup 43. Cup 43 is securelyheld, as by screws, 46-46 to the side of housing 2|, and therebyadjustments can be made in the, tension of spring 26. In Figures. 4 and5 the lateral projection on thev end of, a switch-stick isshown at 48.

Operation is as follows:

A. The normal positions of the various members are as shown in fulllines in Figures 2, 6, 7 and 8. Figure 1 shows normal conditions exceptthat latch I5 is held by projection 26 in the position shown in Figure5, instead of hanging freely as in Figure 6.

B. Power is supplied through each of the three dropout fuses. Whenoverload occurs and ruptures one of the fuses, the fuse container dropsin the well known manner to the fully open position shown by dottedlines in Figure 2.

C. In so falling the fuseholder develops considerable speed, and so ithits a hard hammerblow against its respective trip member I2, therebyrotating operating bar It with considerable force. This rotatesoperating shaft 33 counterclockwise (see Figures 2, 6 and 8) against thebias of spring 35, and thereby it breaks the lock of the toggle holdingmechanism that restrains the large operating spring 25. Thereupon spring25 turns shaft 23 clockwise and with it grounding bar 9, so that allgrounding members I! are brought against contacts 'i'!, and this blowsany fuses that were intact and the circuit is fully opened.

After completion of the grounding action, the latch is is in theposition shown in Figure 3. To reset, a switch stick end 48 is insertedin ring ill and pushed upwardly. Since ring I! is not directly belowpivot I i, latch I5 is pushed into position shown in Figure 4, andfurther upward motion of the switch stick causes crank [3 to rotate andto wind up spring 26 until pivot 39 reaches the center-line positionwith its toggle. Spring 35 then pushes the toggle past center into itsreset position as shown in Figure 8. Spring 35 also prevents thedelicately set toggle look from becoming released by vibration or otheraccidental causes. Screw 38 can be adjusted to alter the distance pastcenter which the toggle can go. This makes possible a very closeadjustment, and since the latch I5 is not connected with the toggle thefunctions of latch and toggle are independent of one another.

At the same time latch l5 has reached the position where the hole in I5slips over projection 29, which has meanwhile been brought to its resetposition. There is a slight springiness in various members, and so aspressure from the switch-stick is relaxed latch !5 becomes held byprojection 26. This holds projection 20 down and holds crank I3 up.Under such conditions accidental release of grounding bar 9 isprevented. Therefore the lineman can re-fuse all fuseholders withoutfear that an accidental ground- When re-fusing is completed the linemandescends, and with a switch-stick he engages ring i8 as shown in Figure5 and pulls latch l5 away from projection 25] so that latch I5 hangs asshown in Figure 6. Thus normal conditions are restored.

We claim:

1. In a multiple conductor electric circuit, a multiplicity of fuseseach comprising a dropout fuseholder and a fuselink therein, a groundingmechanism adjacent to and coordinated with the said fuses, whichmechanism includes a multiplicity of grounding members interconnectedand simultaneously movable, a single spring biasing all the groundingmembers towards grounding position, a single adjustable holdingmechanism resisting the bias of said spring, a multiplicity of dinterconnected trip members each operable by the dropout motion of itsrespective fuseholder, and members connecting the trip members with theholding mechanism, whereby the force of the dropout motion of any of thefuseholders will directly cause the release of the single holdingmechanism so that the spring moves all grounding members to groundingposition.

2. In combination with a multiple-conductor electric circuit whichincludes adjacent dropout fuses; a grounding device which includes agrounding bar and attached thereto a multiplicity of grounding membersmovable simultane ously into and out of contact each with its respective conductor, a single spring biasing the grounding memberstowards grounding position, holding mechanism to resist the bias of thespring, automatic means operable by the blowing of any one of the fusesto release the holding mechanism, and a single reset crank secureddirectly to the grounding bar in spaced relation from the biasingspring.

3. In combination with a multiple-conductor electric circuit whichincludes adjacent fuses, a grounding device which includes a groundingbar biased to rotate and with a multiplicity of grounding memberssecured thereto, holding means to prevent rotation of said groundingbar,a rotatable operating bar adjacent to the grounding bar, and a latchpivotally supported by the rounding bar and movable to rotate thegrounding bar and engageable with the operating bar to interlock thegrounding bar and the operating bar against rotation when the device isother wise in reset condition; the said latch being then disengageableat will from the operating bar.

4. In combination with a multiple conductor electric circuit which has amultiplicity of adjacent dropout fuses each cf which includes afuseholder which drops downwardly when its fuselink has been ruptured; agrounding device which has a multiplicity of grounding members operablesimultaneously for grounding all of said conductors, said deviceincluding also biasing means to bias the grounding members towards thesaid conductors, and holding mechanism to restrain the said biasingmeans, together with a multiplicity of trip members each operable by thefalling motion of its respective fuseholder and each so connected withthe said holding mechanism that the energy of the falling fusehclder isdirectly transmitted to the said holding mechanism to release it and soto allow the said biasing means to move all grounding members intogrounding contact with said conductors.

' 5. In combination with a multiple conductor electric circuit whichincludes a multiplicity of dropout fuses each with its fuseholder andeach in circuit with its respective conductor; a grounding mechanismwhich includes a multiplicity of grounding members operablesimultaneously to ground each conductor in the circuit, a singleoperating spring biasing all the grounding members towards the saidconductors, a single holding mechanism to restrain the said operatingspring, and a multiplicity of trip members each operable by the dropoutmotion of its respective fuseholder to release the same said holdingmechanism and thereby to allow the single operating spring to move allgrounding members each into grounding contact with its respectiveconductor.

. 6. In combination with a multiple-conductor 'electric circuit whichincludes adjacent fuses,

a grounding device which includes a grounding bar b ased torotate andwith a multiplicity of 5 grounding members attached thereto, a singletoggle holding mechanism to prevent rotation of said grounding bar and,independent of said toggle, latch means operable at will to lock thegrounding bar against rotation or to release the said lock.

7. In combination with a multiple-conductor electric circuit whichincludes adjacent fuses, a grounding device which includes a groundingbar biased to rotate and thereby to ground a multiplicity of conductors,a single toggle holding mechanism to prevent rotation of said groundingbar, adjustable stop means to limit the travel of the toggle pastcenter, a relatively light spring biasing the toggle past center, and,removed from the toggle and its adjustable stop, latch means operable atwill to look the grounding bar against rotation.

8. In combination with a multiple-conductor electric circuit whichincludes adjacent dropout fuses, a grounding device which includes a r0tatable grounding bar with a multiplicity of grounding members securedthereto, spring means biasing the grounding members towards groundingposition, a single holding mechanism to resist the bias of the springmeans, a rotatable operating bar adjacent to the grounding bar, ahousing which partially supports the grounding bar and the operating barand which also encloses the said holding mechanism, and a manuallyoperable latch spaced away from the housing and operable either tointerlock the grounding bar and the operating bar to prevent rotation ofthe grounding bar, or to release the said interlock.

9. In combination with a multiple-conductor electric circuit whichincludes adjacent dropout fuses, a grounding device which includes agrounding bar with a multiplicity of grounding members secured theretoand movable simultaneously into and out of grounding position, andadjacent thereto an operating bar with a multiplicity of trip memberssecured thereto, spring means biasing the grounding bar towardsgrounding position, a single toggle holding mechanism to resist the biasof the spring means when the toggle is past center, adjustable stopmeans to limit the motion of the toggle past center, 1e said tripmembers bein respectively directly in the path of the fallingfuseholders, and a connection from the operating bar to the togglewhereby the energy of any falling fuseholder is transmitted directlyagainst the toggle to force it back past its center position and therebyto release the said spring means.

10. A grounding device as in claim 9, which includes also a relativelylight spring operable to bias the toggle towards its holding positionpast center.

WILLIAM D. MATTHEWS. THOMAS E. CURTIS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,954,634 Lemmon et al. Apr. 10, 1934 2,089,387 Lemmon Aug.10, 1937 2,523,943 Choppa Sept. 26, 1950 2,571,794 Turner Oct. 16, 1951

